With barely 72 hours to go before Canada goes to the polls on Monday, it is uncertain whether Prime Minister Stephen Harper’s Conservative Party will hang onto the government after nine years or whether the Liberal Party will return to power under its legacy heir: Justin Trudeau, 45, son of the late Prime Minister Pierre Elliot Trudeau.

Strong on everyone's minds on both sides of the border: the Keystone XL pipeline to transport oil from Alberta, Canada to the U.S.

What makes the politics of Keystone different in the U.S. from Canada is that where opposition and support for the pipeline among Americans is divided along party lines, the two major party chieftains in Canada — Harper and Trudeau — are both Keystone backers.

Seven years after the TransCanada Corporation filed its permit to begin construction of the Keystone XL pipeline in the U.S., politicians remain bitterly divided over proceeding with it.

Most Republicans in Congress and running for president favor completing the pipeline, while Hillary Clinton and Bernie Sanders left no doubt about their opposition to Keystone during the Democratic presidential debate Oct. 13.

The Keystone XL system currently has two missing links: the Northern route, from Alberta's oil sands region to Steele City, Neb., and the Gulf Coast Project, from Cushing, Okla., to the Gulf Coast.

In Canada, however, Keystone is viewed differently. For years, Harper has called its completion a “no brainer,” noting that the pipeline is backed by most Americans and the State Department’s assessment has concluded its impact on the environment is not dangerous.

“It has as much support as I think any economic policy you can imagine in the United States,” Harper spokesman Kory Teneycke told the Toronto “Star” last month, “That’s why we think in the longer term it will be built.”

But Trudeau and his party platform also embrace Keystone XL. In what many pundits see as a clear break from his vigorous environmentalist predecessors as Liberal leader (former Environment Minister Stephane Dion and political scientist Michael Ignatieff), Trudeau has repeatedly vowed to fight for Keystone XL with the corollary that he will add new environmental policies at home that might convince President Obama to relent and grant the permit.

As if to assuage the environmentalist element within his party, Keystone backer Trudeau opposes a northern gateway proposal that would carry oil across the Rockies for transport to Asian markets via oil tankers through British Columbia’s northern coastal waters.

Like Tom Mulcair, leader of the far-left New Democratic Party, Trudeau has so far taken no position on the Energy East project that would ship Alberta oil to Canadian east coast refineries and from there transport it to markets throughout the world.

“Justin Trudeau has led the Liberal Party in such a way as to cling to the political center,” Christopher Sands, senior research professor and director of the Washington D.C.-based Center for Canadian Studies at Johns Hopkins University, told me, “and interestingly, Thomas Mulcair has positioned the [historically-far left] New Democratic Party close to the center as well.”

The pivotal issue on which the centrist campaigns of opposition leaders Trudeau and Mulclair differ, added Sands, “is that Mulcair will not fight for Keystone XL and Trudeau says he will.”

A just-completed Nanos Poll (conducted for the “Globe and Mail” newspaper and Canadian TV) showed Trudeau’s Liberals leading with 37.1 percent among likely Canadian voters, compared to 29.4 percent for Harper’s Conservatives. Trailing is Mulcair’s NDP, with 23.7 percent.

“So if Trudeau forms a government, it will be a minority government,” said Sands, “That said, I think that Harper is being underestimated again. He has a well-financed and disciplined voter turnout model, and the surge for Trudeau will motivate his base to vote. As in Britain, polls that show overall percentages are tricky to translate into constituencies and seats.”

John Gizzi is chief political columnist and White House correspondent for Newsmax.